1. Technical Field
The present invention relates to a power semiconductor module and a method of manufacturing the power semiconductor module.
2. Description of the Related Art
The recent development of the power electronics industry is allowing the miniaturization and densification of electronic products to be achieved. Accordingly, a method of reducing the size of an electronic device itself, and also a method of installing as many devices and wires as possible in a given space has become important to the design of a semiconductor package. The density of semiconductor devices and wires of this package has been becoming greater and greater, and a large amount of heat is generated in the package. Since the heat affects the lifespan and operation of an electronic product, the dissipation of heat in the high density package is important.
FIG. 1 is a sectional view illustrating a conventional power module package. As shown in the drawing, semiconductor devices including a power device 15 and a control device 13 are soldered or bonded to the metallic surface of a direct copper bonding (DCB) circuit board 10. The circuit board 10 must have thermal conductivity in addition to electrically insulating the semiconductor devices from a base plate 20 of the module package. Here, the base plate 20 and the circuit board 10 are insulated by a ceramic material such as Al2O3, AlN, SiN, or SiC or organic material such as epoxy or polyimide.
The top surfaces of the semiconductor devices 13 and 15 are connected to the structured area of the metallic surface through thin aluminum connecting wires. Further, a passive device such as a gate resister or a current/temperature sensor may be integrated into the module, and a protective and drive circuit device and circuit may be also integrated in the module.
Such a conventional power module package is constructed so that a plurality of power devices 15 and diodes are attached to one DCB board 10 through soldering 17, are attached to the base plate 20 made of copper using solder 23 so as to provide good thermal properties and are covered by a housing. The devices 13 and 15 are electrically connected to the board 10 using wedge bonding, and the board 10 is electrically connected to a terminal 27 of the housing. The semiconductor devices 13 and 15 and wires are encapsulated by silicone gel, and a heat sink 25 is attached to the back of the base plate 20.
However, the conventional power module package constructed as described above has the following problems.
As the package is miniaturized, the number of semiconductor devices placed in the same amount of space becomes increased, so that a large amount of heat is generated in the package. The heat sink is provided on only the lower portion of the package, so that heat cannot be efficiently dissipated.
Further, as the DCB board 10 is used, an expensive and large copper plate 20 is required for the dissipation of heat. Moreover, the manufacturing process is complicated because the two bonding processes of bonding the semiconductor devices to the DCB board and bonding the DCB board to the base plate must be performed. Further, because of the bonding interface 17 between the semiconductor devices 13 and 15 and the DCB board 10 and the bonding interface between the DCB board 10 and the base plate 20, heat dissipating characteristics are deteriorated.